(a) Field of the Invention
The present invention relates to a Fe—Si alloy powder. More particularly, the present invention relates to a method for further easily manufacturing a Fe—Si alloy powder.
(b) Description of the Related Art
A Fe—Si alloy, that is, silicon steel is a soft magnetic material with excellent permeability and electrical conductivity so that it is used as an iron core of various electric devices such as a transformer, a generator, a motor, and a switch power. In order to manufacture as an iron core, the Fe—Si alloy is manufactured in the form of a sheet or a powder. The sheet-shaped Fe—Si alloy is classified into an oriented silicon steel sheet plate and a non-oriented silicon steel sheet. Since the amount of silicon in the oriented silicon steel sheet is about 3 wt %, the core loss is low and thus the oriented silicon steel sheet is used as an iron core of a transformer. When a soft magnetic material with a low core loss is used as a material or a rechargeable battery or a motor applied to an electric vehicle, energy loss can be reduced and energy efficiency in driving of the motor can be increased. However, the oriented silicon steel sheet cannot be used as a material or a rotor due to magnetic anisotropy. On the contrary, the non-oriented silicon steel sheet has low spatial anisotropy of magnetic, and therefore it is usually used in a rotor of an electromotor.
The silicon steel has a magnetic characteristic that is changed according to the amount of silicon. When the silicon contains 6.5 wt % is Si, the silicon has large electrical resistance and therefore a current loss among the core loss is decreased and the core loss at high frequency is decreased. In addition, magnetostriction is reduced so that noise and vibration can be reduced. However, when the amount of Si in the silicon steel is increased, the silicon steel becomes fragile so that cold rolling of the silicon steel cannot be easily performed. Thus, the silicon steel containing a large amount of Si is manufactured by manufacturing a silicon steel sheet of 3 wt % and then adding silicon to the silicon steel sheet.
A silicon steel containing silicon of less than 3 wt % is used as a representative soft magnetic material in an iron core of various electric devices such as a transformer, a generator, a motor, or a switch power. The silicon steel is relatively inexpensive compared to other soft magnetic materials such as pure iron, Ni—Fe, and Fe—Al—Si and has an excellent magnetic characteristic so that it has high utility.
It is well known that the core loss is decreased when the amount of Si in the silicon steel is increased. This is because that magnetic anisotropy and crystalline anisotropy of the silicon steel are decreased and electrical resistance is increased as the amount of Si is increased. When the amount of silicon in the silicon steel is increased from 3 wt % to 6.5 wt %, the current low is rapidly decreased while the electric resistance is increased from 48 μΩ·m to 82 μΩ·m, and the core loss in high frequency is decreased and the magnetostriction becomes close to zero. Accordingly, noise and vibration can be reduced so that the Fe—Si alloy containing silicon of 6.5 wt % is almost an ideal soft magnet alloy. However, when the amount of silicon is increased, the alloy becomes fragile so that silicon steel containing silicon of higher than 4 wt % cannot be easily cold-rolled.
In order to solve such formability of the silicon steel, a powder core is used. However, a powder core for silicon-rich silicon steel has bad formability and therefore the concentration of the powder core is decreased due to deformation deterioration during compression molding. A Fe—Si alloy powder can be manufactured using grinding, gas spraying, and mechanical alloying, but the gas spraying is generally used in consideration of the shape of the powder and economic efficiency of the process.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.